Howe was sent to North America in March 1775, arriving in May after the Revolutionary War broke out. After leading British troops to a costly victory in the Battle of Bunker Hill, Howe took command of all British forces in America from Thomas Gage in September of that year. Howe's record in North America was marked by the successful capture of both New York City and Philadelphia. However, poor British campaign planning for 1777 contributed to the failure of John Burgoyne's Saratoga campaign, which played a major role in the entry of France into the war. Howe's role in developing those plans, and the degree to which he was responsible for British failures that year (despite his personal success at Philadelphia) have been a subject of contemporary and historic debate.

He resigned his post as Commander in Chief, North America, in 1778, and returned to England, where he was at times active in the defence of the British Isles. He served for many years in Parliament, and was knighted after his successes in 1776. He inherited the Viscountcy of Howe upon the death of his brother Richard in 1799. He married, but had no children, and the viscountcy was extinguished with his death in 1814.